View conversion to SwiftUI

[NattyNarwhal]

Downloads view has been converted and it seems to work pretty well.

• Onboarding: Low-stakes. Done
• Preferences: I have this working in a Playground, but to get the proper Settings view toolbar with a TabView involves conversion to the SwiftUI lifecycle instead of the AppKit one, or manually frobbing NSToolbar (gross).
• Tracklist: Good low-risk opportunity to use tables bound to an array. Will probably involve a refactor of SBPlayer in Swift to expose the tracklist as an @ObservableObject?
• Library views (Music, ServerLibrary, etc.): Would involve a lot of @FetchRequest...
• Database: Would be a good way to clean up the awful mess there. Wiring up sheets, subviews, and selectors sounds nightmarish though.

Concerns would be:

• We have extensive NSTableView customization and common patterns, how hard would these be with SwiftUI Table?

[NattyNarwhal]

I have a prototype of Database in a SwiftUI test project with:

• view switching in sidebar
• enumerates playlists in servers

But:

• toolbar, right sidebar, and actions not implemented yet

[NattyNarwhal]

SwiftUI has a very annoying issue for the tracklist (and probably playlist) case, where you can't really have multiple of the same tracks in whatever collection the Table/List represents, because the selection is based by a Set<SBTrack>, not by an index. It'd need a data model change, or regress to the pre-index change. Might have to play with .enumerated() sometime...

[NattyNarwhal]

Another issue is that Table requires macOS 12. We still support 11, but I don't know if it'd be worth dropping it. App Store users look to be mostly on 12 or 13.